The embattled head of the Internal Revenue Service blames faulty technology for what he called serious problems under investigation by Congress, the Justice Department and the Treasury inspector general.

John Koskinen told CNN's Wolf Blitzer on Thursday that he apologized to anyone who had their application for tax-exempt status held up by IRS targeting of political labels.

"The improper criteria used to highlight organizations for investigation just by their name was a mistake," Koskinen said. "I apologize to anybody who ever had their applications held up needlessly. Everybody needs to be confident that the IRS is going to treat them fairly no matter who they are. Republicans, Democrats, whatever organization they belong to. So it's a serious matter."

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However, he maintained that evidence uncovered so far by six investigations found no involvement by the White House, as alleged by some Republicans.

In particular, GOP critics contend a hard drive crash that wiped out e-mails of the woman at the center of the controversy -- former IRS official Lois Lerner -- looked like a cover-up.

"It is suspicious. When we uncovered it, we pursued evidence," Koskinen said, adding that the agency also looked at other hard-drive failures in recent years. "I think we need to pull all this together, see what we know and proceed."

At the same time, he noted technology problems occurred regularly, with 2,000 hard drives failing so far this year at the agency, which has about 90,000 employees.

Congressional Republicans pummeled Koskinen with questions and accusations this week, all but accusing him of perjury. But he hit back at committee hearings and in the CNN interview.

"It's not my intention at all to play games with the Congress," he said, adding that "people need to feel comfortable that it's not a politicized agency, that it treats people fairly whoever they are."

Asked by Blitzer whether he regretted taking the job, Koskinen joked he should have read the fine print ahead of time. No regrets, he added, citing the need to fulfill an important public service.

A government veteran, the 74-year-old Koskinen is taking the brunt of congressional pressure after the agency admitted it lost thousands of e-mails wanted by lawmakers investigating the targeting scandal.

Rep. Paul Ryan, a Wisconsin Republican, flat out questioned whether Koskinen was being truthful with Congress, and Darrell Issa, the Oversight chairman, called him out for being evasive.

On Thursday, Koskinen repeated his belief that an independent prosecutor would be unnecessary and a waste of taxpayer dollars with the other investigations underway.

Republican Sen. Ted Cruz of Texas said Thursday that Attorney General Eric Holder, a frequent target of GOP attacks, should be impeached for refusing to appoint a special prosecutor to investigate the missing Lerner e-mails.

"Make no mistakes. These e-mails haven't just been lost," Cruz said on the Senate floor. "These e-mails have been deleted, taped over and the hard drive physically destroyed, according to public news reports."

Asked by Blitzer whether a criminal investigation was warranted, Koskinen replied: "I don't think ... at this time there's any evidence of that."

Lerner, who ran the division that carried out the IRS targeting, resigned last year after the Treasury Department's inspector general found those working under her used "inappropriate" criteria to scrutinize certain groups, particularly those with conservative political names. Since then, she has refused to testify at hearings, invoking her constitutional right not to do so.

Earlier this month, the IRS told Congress that a 2011 crash of Lerner's computer hard drive meant that e-mails until that point had been lost. The IRS targeting was first noticed by the agency after that time.

Koskinen noted Thursday that the agency had recovered 24,000 Lerner e-mails by other means and was cooperating fully with all investigations of the matter.

When Blitzer noted that taxpayers believe the IRS would never accept the excuse of a hard drive crash for filing an improper return, Koskinen responded that the agency tries to work with people to resolve the situation.

"We historically, if a taxpayer has lost electronic records, have said if you have other indications and evidence of what went on, we'll take that from you," he said. "If you lose a document, it doesn't mean you lose the argument. We actually work with taxpayers to say we'll look at other evidence ... and if we can find any evidence to support your case -- and, in fact, if the circumstances support your case, we'll support you and you won't have any problems."

On Wednesday, a Republican congressman revealed Lerner e-mails that asked whether the IRS should look into an invitation for GOP Sen. Charles Grassley of Iowa to appear at a seminar.

The disclosure of the e-mail exchanges by House Ways and Means Committee Chairman Dave Camp of Michigan further inflamed GOP sentiment against Lerner.

However, it was not clear from the e-mails whether Lerner was referring to an audit of Grassley personally or the group that invited him and was possibly offering to pay for his wife to attend. Her lawyer said Lerner acted appropriately, and Koskinen said Thursday the intent was unclear.

Democrats accuse House Republicans of politicizing the IRS investigation, noting that some liberal seeking tax exempt status also were also targeted by the agency.